Intense and coherent terahertz (THz) radiation was observed from
the intrinsic Josephson junction (IJJ) system of the single
crystalline high-$T_{c}$ superconductor
Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$
(Bi-2212).\footnote{L. Ozyuzer et al., Science \textbf{318,}
(2007) 1291.}$^,$\footnote{K. Kadowaki et al., Physica C
\textbf{468,} (2008) 634.} In the present work, we demonstrate
the importance of the THz radiation from inner branching
structures of the $I-V$ characteristic curve of the IJJ system.
The radiation frequency has previously been thought to be
uniquely constrained to the mesa size, but it turns out in the
inner branches that it varies very flexibly and widely perhaps
according to the inductive and capacitive coupling strength
existing in the mesa itself. Therefore, the radiation frequency
does not follow the previously established cavity resonance
condition. This new experimental feature may provide a unique
opportunity to understand the dynamical nature of IJJ as
well as the mechanism of high-$T_{c}$ superconductivity in this
particular Bi-2212 compound.

To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.A41.10